(a) Field of the Invention
The present invention relates to a control method for a hybrid vehicle that enables a continuous shift of a transmission by using an engine, a first motor-generator, and a second motor-generator.
(b) Description of the Related Art
Generally, an automatic transmission utilizes hydraulic pressure to shift gears in multiple steps to output the appropriate amount of torque from a rotation torque of an engine/motor based on various driving conditions. Some hybrid vehicles utilize two motor/generators (MG) and one engine that are connected through a planetary gear. In particular, the motor/generator is control in order to achieve a continuously variable shifting.
The engine, the first and second motor/generators, and two planetary gear sets are used to continuously vary the output speed of a transmission according to various driving conditions. Here, the speeds of each the first and second motor/generators are controlled.
The first motor/generator is speed-controlled according to the driving conditions of the engine and the second motor/generator is torque-controlled together with the engine to control the entire torque output. Meanwhile, while the first motor-generator is being used to control a driving point control of the engine, in a flexible hybrid system (FHS4) there is still no method for effectively setting a base motor torque.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.